<SEC-DOCUMENT>0000045876-18-000134.txt : 20181023
<SEC-HEADER>0000045876-18-000134.hdr.sgml : 20181023
<ACCEPTANCE-DATETIME>20181023150906
ACCESSION NUMBER:		0000045876-18-000134
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20181022
FILED AS OF DATE:		20181023
DATE AS OF CHANGE:		20181023

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			HAZNEDAR CAROLANN I
		CENTRAL INDEX KEY:			0001756619

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-03970
		FILM NUMBER:		181134011

	MAIL ADDRESS:	
		STREET 1:		350 POPLAR CHURCH ROAD
		CITY:			CAMP HILL
		STATE:			PA
		ZIP:			17011

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			HARSCO CORP
		CENTRAL INDEX KEY:			0000045876
		STANDARD INDUSTRIAL CLASSIFICATION:	FABRICATED STRUCTURAL METAL PRODUCTS [3440]
		IRS NUMBER:				231483991
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		350 POPLAR CHURCH ROAD
		CITY:			CAMP HILL
		STATE:			PA
		ZIP:			17011
		BUSINESS PHONE:		7177637064

	MAIL ADDRESS:	
		STREET 1:		350 POPLAR CHURCH ROAD
		CITY:			CAMP HILL
		STATE:			PA
		ZIP:			17011
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_154032173073126.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-10-22</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000045876</issuerCik>
        <issuerName>HARSCO CORP</issuerName>
        <issuerTradingSymbol>HSC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001756619</rptOwnerCik>
            <rptOwnerName>HAZNEDAR CAROLANN I</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>350 POPLAR CHURCH ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CAMP HILL</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>17011</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2018-10-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2444</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2444.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2444</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents restricted stock units granted under the 2016 Non-Employee Directors' Long-Term Equity Compensation Plan. Each restricted stock unit shall vest at the close of business on the earlier of (i) the first anniversary of the grant date or (ii) the annual meeting of the Issuer's stockholders in the year immediately following the year of the grant date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Carolann I. Haznedar</signatureName>
        <signatureDate>2018-10-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>powerofattorney.htm
<DESCRIPTION>POWER OF ATTORNEY CAROLANN HAZNEDAR
<TEXT>
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<pre>
POWER OF ATTORNEY


    The undersigned, a director and (or) officer of Harsco Corporation, a Delaware corporation (the "Company") appoints the following individuals, with full power to each of them to act alone, as his or her true and lawful attorneys-in-fact and agents to execute and file on behalf of the undersigned all Forms 3, 4 and 5 and any amendments thereto that the undersigned may be required to file with the Securities and Exchange Commission, and any stock exchange or similar authority, as a result of the undersigned's ownership of or transactions in securities of Harsco Corporation. The authority of the following individuals under the Power of Attorney shall continue until the undersigned is no longer required to file Forms 3, 4 and 5 with regard to the undersigned's ownership of or transactions in securities of Harsco Corporation, unless earlier revoked in writing. The undersigned acknowledges that the following individuals are not assuming any of the undersigned's responsibilities to comply with Section 16 of the Securities Exchange Act of 1934.

    The following employees of Harsco Corporation:

Senior Vice President and General Counsel, Chief Compliance Officer & Corporate Secretary of the Corporation
        Vice President, Assistant General Counsel & Assistant Corporate Secretary
         Corporate Governance Associate

    This authorization shall supersede all prior authorizations to act for the undersigned with respect to securities of the Company in these matters.

    IN WITNESS WHEREOF, I have hereunto set my hand this 22nd day of October 2018.



        Carolann I. Haznedar
</pre>
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